Process for enhancing control over a braked vehicle

Abstract

Brake pressure is varied briefly by means of pressure pulses at regular intervals during phases when brake pressure is otherwise maintained constant, and any variations in transverse acceleration at each axle are determined. These variations at the axles are used to modify the wheel slip by varying the brake pressure in order to increase stability while retaining an adequate steerability reserve or vice versa.

We claim: 
     
       1. Method of improving control of a vehicle during braking, said vehicle having a front axle, a rear axle, at least one wheel at each axle, and brakes which are controlled by brake pressure at each wheel, said wheels exhibiting slippage which determines stability and steerability of the vehicle, said method comprising changing said brake pressure in a pressure pulse during phases when said brake pressure is otherwise maintained constant,   determining a transverse acceleration at each axle before and after said pulse,   determining for each axle changes in transverse acceleration after said pulse, as compared to before said pulse,   changing the brake pressures in accordance with said changes in transverse acceleration to modify wheel slippage at each axle so that the steerability is increased when an adequate stability is determined and so that the stability is increased when an adequate steerability is determined.   
     
     
       2. Method of improving control of a vehicle during braking, said vehicle having a front axle, a rear axle, at least one wheel at each axle, and brakes when are controlled by brake pressure at each wheel, said wheels exhibiting slippage which determines stability and steerability of the vehicle, said method comprising changing said brake pressure in a pressure pulse during phases when said brake pressure is otherwise maintained constant,   determining a transverse acceleration at each axle before and after said pulse,   determining a transverse stability reserve for each axle from changes in transverse acceleration after said pulse, as compared to before said pulse,   determining a stability reserve and a steerability reserve from the transverse stability reserve for each axle,   changing the brake pressure to modify wheel slippage at each axle so that the steerability reserve is increased when an adequate stability reserve is determined and so that the stability reserve is increased when an adequate steerability reserve is determined.   
     
     
       3. Method of improving control of a vehicle during braking, said vehicle having a front axle, a rear axle, at least one wheel at each axle, and brakes which are controlled by brake pressure at each wheel, said wheels exhibiting slippage which determines stability and steerability of the vehicle, said method comprising changing said brake pressure in a pressure pulse during phases when said brake pressure is otherwise maintained constant,   determining a yaw acceleration of the vehicle before and after said pulse,   determining for each axle changes in yaw acceleration after said pulse, as compared to before said pulse,   changing the brake pressures in accordance with said changes in yaw acceleration to modify wheel slippage at each axle so that the steerability is increased when an adequate stability is determined and so that the stability is increased when an adequate steerability is determined.   
     
     
       4. Method of improving control of a vehicle during braking, said vehicle having a front axle, a rear axle, at least one wheel at each axle, and brakes which are controlled by brake pressure at each wheel, said wheels exhibiting slippage which determines stability and steerability of the vehicle, said method comprising changing said brake pressure in a pressure pulse during phases when said brake pressure is otherwise maintained constant,   determining a yaw acceleration of the vehicle before and after said pulse,   determining a transverse stability reserve for each axle from changes in yaw acceleration after said pulse, as compared to before said pulse,   determining a stability reserve and a steerability reserve from the transverse stability reserve for each axle,   changing the brake pressure to modify wheel slippage at each axle so that the steerability reserve is increased when an adequate stability reserve is determined and so that the stability reserve is increased when an adequate steerability is determined.